Concrete insert



June 2, 1970 J. MERRILL, SR 3,514,917

I CONCRETE INSERT Filed Sept. 11, 1967 3 Sheets-Shect 1 //v l/EA/ r02JAMES Meek/1.4, 53?.

June 2, 1970 J, ME mL 5R 3,514,917

CONCRETE INSERT Filed Sept. 11, 1967 3 Sheets-Sheet 2 FIG. 7

him]

mum/7oz JAMES MEQQ/L L, 5E.

June 2, 1970 J. MERRILL. SR 3,514,917

CONCRETE INSERT Filed Sept. 11, 1967 5 Sheets-Sheet :5

D 'i 1' P1176118.

//v l/EN TOR JAMES MERR/LL, 5A.

/%Mw ww A Tram/5 United States Patent 3,514,917 CONCRETE INSERT JamesMerrill, Sr., 1505 Randall Way, West Covina, Calif. 91790 Filed Sept.11, 1967, Ser. No. 666,698 Int. Cl. E04b 1/38 U.S. Cl. 52704 5 ClaimsABSTRACT OF THE DISCLOSURE An insert to be cast in a ceiling-floor slabof a reinforced concrete structure for attaching a load support, such asa hangar, to the slab, the insert having a combined shield andsupporting base for supporting the insert on reusable pan joists overwhich a concrete slurry is poured to form the slab and shielding theload attachment means of the insert against b ockage by the slurry, andthe base being plastically deformable or otherwise adjustable tocompensate for irregularities in the pan joists. A concrete insert and aload hanger of the character described embodying an acoustic barrier forinhibiting transmission of acoustic vibrations from the supported loadto the supporting slab.

This invention relates generally to means for attaching loads to aconcrete structure, such as a ceiling-floor slab of a reinforcedconcrete building structure. The invention relates more particularly toan improved insert and hanger for the purpose described.

As will appear from the ensuing description, the invention may beemployed to advantage in a variety of applications. However, theinvention finds primary utility in attaching loads, such as water pipes,electrical conduits, and the like to the ceiling-floor slabs of areinforced concrete building structure. For this reason, the inventionwill be disclosed in this particular connection.

It is common practice in the building construction trade to attach waterpipes, electrical conduits, and the like to an overhead ceiling-floorslab of a reinforced concrete building structure, that is a concretepartition or slab which forms the ceiling of a lower building level andthe floor of the adjacent upper level, by means of load hangers whichare attached to inserts embedded in the slab. In the present disclosure,these two different attachment means, i.e., the inserts and the hangers,are referred to generically as supports. The present invention is aimedat avoiding or curing certain inherent deficiencies in the existingsupports of this class.

Consider first the existing concrete inserts. Generally speaking, thebuilding construction trade employs two different techniques for formingthe ceiling-floor slabs of a reinforced concrete building structure. Onetechnique utilizes reusable, so-called pan joists. These joists areessentially metal planks or plates which are supported on a scaffold andjoined edge to edge so as to constitute the lower wall of a concreteform. A concrete slurry is poured over these pan joists to form aceiling-floor slab of a reinforced building structure. Prior to pouringthe slab, the slab inserts to be installed are properly located over andsupported on the pan joists. Concrete slurry is then poured over the panjoists and about the inserts and allowed to set to produce a finishedslab having the inserts embedded therein. After setting, the pan joistsand their supporting scaffold are removed for subsequent reuse. Removalof the pan joists exposes the embedded inserts for attachment thereto ofceiling hangers, or the like.

The existing concrete inserts of this kind have several inherentdeficiencies. One of these deficiencies resides in the difficultyinvolved in retaining the inserts in the 3,514,917 Patented June 2, 1970proper vertical attitude while the slab is being poured. Thus, reusablepan joists are subjected to much abuse and are frequently bent orotherwise deformed in use. As a consequence, when the inserts to beinstalled in a concrete ceiling-floor slab are supported on the panjoists prior to pouring the slab, the inserts tend to assume a varietyof attitudes, depending upon the bends or other irregularities in thepan joists. Various techniques have been devised to compensate for suchbends and irregularities, thus to permit the inserts to be initiallylocated in the proper vertical attitude. All of these existingtechniques, however, are unsatisfactory owing to their complexity, cost,time consumption, and other factors.

One aspect of this invention is to provide an improved concrete insertwhich avoids the above problems. According to this aspect, the insert isequipped with a base for supporting the insert on pan joists duringpouring of a concrete slurry over the joists to produce a concrete slab.This base is readily adjustable, as by bending or other plasticdeformation, to locate the insert in the proper vertical attituderegardless of bends or other irregularities in the pan joists.

Another problem which is frequently encountered with the existingconcrete inserts is blockage of the inserts by the concrete. Thus, atleast some existing inserts are equipped with a box or housing-likeenclosure whose function is to shield the hanger attachment means of theinserts against blockage by the concrete slurry being poured. Thisenclosure or shield has an open side through which the attachment meansare exposed after the pan joists are removed. Much difficulty has beenexperienced in the past due to leakage of concrete slurry into the openside of the shield. This leakage slurry, when set, had to be chippedaway or o'herwise removed to expose the load attachment means of theinserts.

An important aspect of the present invention is to provide a concreteinsert which is immune to this problem of concrete blockage. Accordingto this aspect, the invention proivdes an insert having a completelysealed or hermetic enclosure for shielding the insert hanger attachmentmeans against the concrete slurry which is poured about the insert. Thishermetic shield has a removable closure, such as a knock-out plug, inone end. The closure is exposed when the pan joists are removed, wherebythe hanger attachment means of the insert are exposed by knocking out orotherwise removing the closure.

Sound transmission from the load or loads being supported to thesupporting concrete rfloors and ceilings of reinforced concretestructures is a serious problem with the existing concrete inserts andhangers of the kind under discussion. This is due to the fact that theexisting inserts and hangers provide a highly effective acoustictransmission path from the load to the slab. According to a further ofits aspects, the invention provides an acoustically insulated loadsupport of the character described which embodies an acoustic insulatingbarrier between the load and the slab toinhibit transmission of acousticvibrations from the load to the slab. This load support may be either aninsert to be embedded in a newly built reinforced concrete structure ora hanger to be attached to inserts embedded in an existing buildingstructure.

A general object of the invention, then, is to provide an improved loadsupport of the character described.

Another object of the invention is to provide a concrete insert to becast in a ceiling-floor slab of a reinforced concrete building structurepoured with the aid of reusable pan joists, which insert is adjustableto compensate for bends or other irregularities in the joists.

Yet another object of the invention is to provide a concrete insert ofthe character described which is hermetically sealed against blockage ofthe insert hanger attachment means by the concrete in which the insertis cased.

A further object of the invention is to provide a concrete insert andload hanger of the character described which are acoustically insulatedto inhibit transmission of acoustic vibrations from the supported loadto the supporting structure.

Other objects, advantages, and features of the invention will becomereadily evident as the description proceeds.

In the drawings:

FIG. 1 is a vertical section illustrating a pair of the present improvedinserts supported on removable pan joists prior to pouring of a concreteslurry over the joists to form a ceiling-floor slab of a reinforcedconcrete building structure;

FIG. 2 is an enlarged axial section through the righthand insert in FIG.1;

FIG. 3 is an axial section through a modified acoustically insulatedconcrete insert according to the invention;

FIG. 4 is a view in side elevation, partly broken away, of a furthermodified concrete insert according to the invention;

FIG. 5 is a top plan view of the insert in FIG. 2;

FIG. 6 is a vertical section through a further modified concrete insertaccording to the invention illustrating the insert supported onpermanently installed pan joists prior to pouring a concrete slurry overthe joists to produce a ceiling-floor slab of a reinforced concretebuilding structure;

FIG. 7 is a fragmentary enlarged bottom plan view of the insert in FIG.6;

FIG. 8 is a side elevation of an acoustically insulated hanger accordingto the invention illustrating the hanger attached to an existing insertin a reinforced concrete building structure;

FIG. 9 is an enlarged bottom plan view of the hanger with parts brokenaway for the sake of clarity;

FIG. 10 is an enlarged axial section through the hanger; and

FIG. 11 is a side elevation of the hanger.

Referring to FIGS. 1 and 2 of the drawings, there is illustrated to aconcrete insert 10 according to the invention which is designed to becast in a concrete slab 12 that is made by pouring a concrete slurryover reusable pan joists 14 which are joined side by side to provide thebottom wall of a concrete slab form. The insert 10 has a body 16including an upper load bearing member 18 and a lower supporting base20. Extending into the lower end of the load bearing member 18 is athreaded bore 22. This bore forms an attachment means for securing apipe hanger, or the like, to the insert after the latter has been set inthe concrete slab 12.

In use, the insert 10 is supported on the pan joist 14, in the mannerillustrated in FIG. 1. A concrete slurry is then poured over the joistsand about the insert and allowed to set to form a completedceiling-floor slab 12. After the slab has properly set, the pan joistsare removed for subsequent reuse. Removal of the joists exposes theinstalled inserts for attachment thereto of hangers, or the like, whichcarry the loads to be supported.

As noted earlier, one of the problems encountered in installing insertsof the character described resides in the fact that the reusable panjoists 14 are frequently bent or otherwise deformed in use. As aconsequence, it is difficult to locate all of the inserts in the propervertical attitude prior topouring the concrete slurry over the joistsand about the inserts to form a slab. In FIG. 1, for example, theportion of the pan joists 14 on which the left hand insert 10 issupported in FIG. 1 is level. Accordingly, location ofthis left-handinsert in its proper vertical attitude presents no problem. However, theportion ofthe pan joists on which the right-hand insert is supported inFIG. 1 is bent. As a consequence, the insert must be provided with sometype of compensating adjustment to enable the insert to be located inthe proper vertical attitude regardless of bends or other irregularitiesin the pan joists. According to the present invention, this adjustmentis furnished by the insert base 20. In this regard, for example, it willbe observed that the supporting bases of the two inserts 10 illustratedin FIG. 1 are, in effect, adjusted to two different settings whichenable both in serts to be located in the proper vertical attitude eventhough the inserts are not both supported on level portions of the panjoists.

Referring now in more detail to the drawings, the load bearing member 18of the present insert 10 is fabricated from metal or other relativelystrong material and has a generally inverted conical shape. The hangerattachment means or threaded bore 22 of the insert extends axially intothe normally lower, small diameter end of the member. If desired, theupper large diameter end of the member may be provided with outwardlydirected flanges 24 to provide firm anchorage of the insert in theconcrete slab 12. The lower supporting base 20 of the illustratedconcrete insert 10 serves a two-fold function. First, it provides anadjustable support for the insert which enables the attitude of theinsert to be adjusted, in the manner just explained. As will appearpresently, this adjustment is accomplished by plastic deformation orbending of the base. Secondly, the supporting base of the insertprovides a hermetic enclosure or shield which prevents entrance ofconcrete slurry into the hanger supporting bore 22 of the insert whenthe latter is cast in the concrete slab 12.

To these ends, the supporting base 20 of the insert 10 comprises aconical sleeve 26, the upper small diameter end of which is adhe'sivelybonded or otherwise sealed to the lower small diameter end of the loadbearing member 18 of the insert, about the lower open end of the insertbore 22. The lower, large diameter end of the sleeve 26 is closed by awall 28. Extending through this wall is an opening 30 containing aremovable closure 32. The illustrated closure is a knock-out plug whichis sealed about its periphery to the wall of the opening 30, in such away that the plug may be easily pushed out from the opening. It isevident at this point, therefore, that the supporting base 20 of theinsert 10 provides a generally cup-like hermetic enclosure or shieldabout the lower open end of the insert hanger attachment bore 22 forshielding this bore against the entrance of concrete slurry.Accordingly, there is no possibility of blockage of the bore by theslurry when the insert is cast in the concrete slab 12, in the mannerexplained earlier.

As explained above, a second function of the supporting base 20 is topermit adjustment of the attitude of the insert 10 when the latter issupported on the pan joists 14, thus to permit the insert to be locatedin the proper vertical attitude regardless of irregularities in the panjoist. To this end, the supporting base or shield 20 is molded from asuitable flexible plastic which may be deformed, in the mannerillustrated in FIGS. 1 and 2, to provide the required attitudecompensating adjustment for the insert. In some cases, the plasticmaterial of the supporting base may be sufficiently non-elastic, i.e.,plastically deformable, to enable the base to retain its deformed orbent shape. In other cases, it may be desirable to mold plasticallybendable elements or wires 34 within the walls of the base, asillustrated in FIG. 2, to aid the base in retaining its bent shape.

It is now evident that when the present insert 10 is supported on thepan joists 14, the supporting base 20 of the insert may be deformed tolocate the insert in the proper vertical attitude, regardless of bendsor other irregularities in the joist. In this regard, for example, itwill be observed that the left-hand insert 10 in FIG. 1 assumes avertical attitude without any deformation of its supporting base, whilelocation of the right-hand insert in FIG. 1 requires one side of itssupporting base to be deformed to locate the insert in the propervertical attitude. When the concrete slurry is poured over the pan joist14, the slurry flows about the body of the inserts to eflect firmanchorage of the latter in the finished concrete ceiling-floor slab 12.This slab will also contain suitable reinforcing means, such as metalreinforcing rods, which have been omited from the drawings for the sakeof clarity. It is evident that because of the nonuniform cross-sectionof the load bearing member 18 of each insert, that is the changingcross-section of the member in planes normal to its vertical axis, thelatter is firmly anchored against pulling from the slab 12 when thelatter finally sets. This firm anchorage of the load bearing member inthe slab is enhanced by the flanges 24. In addition to supporting theinsert in the proper vertical attitude during pouring of the concreteslurry about the insert, the insert base 20 serves as a shield whichpermits the entrance of the slurry into the hanger attachment bore 22 ofthe load bearing member 18. Accordingly, it is unnecessary to removeconcrete from this opening before using the insert.

After the slab 12 is properly set, the pan joists 14 are removed forsubsequent reuse. When the joists are thus removed, the lower end ofeach installed insert is exposed at the under side of the slab. As aconsequence, the closureor knock-out plug 32 of each insert may bepushed out to expose the hanger attachment bore 22 of the insert throughits hollow supporting base 20. Accord ingly, a threaded hanger rod, orthe like, may be inserted through the base opening 30 and threadedupwardly into the bore 22 to effect firm attachment of the rod to theload bearing member 18 of the insert, and thereby to the concrete slab12.

As noted earlier, transmission of acoustic vibrations from the supportedload to the supported concrete ceilingfloor slab is a problem with theexisting inserts and hangers. According to a further feature of thepresent invention, this problem is alleviated to a high degree byproviding an acoustic insulating barrier between the load and slab. FIG.3, for example, illustrates a modified concrete insert 10a according tothe invention embodying such an acoustic insulating feature. Thismodified insert is identical to the insert 10 just described except forthis acoustic insulation feature. Accordingly, it is unnecessary todescribe the modified insert in detail. Suflice it to say that the loadbearing member 18a of the insert 10a is composed of an outer conicalshell 36a an inner conical element 38a and an intervening conicalbarrier or sleeve 40a of suitable acoustic insulating material, such asrubber or plastic. The outer sleeve 36a and inner element 38:: arefabricated from metal or other relatively strong material. The innerelement contains the threaded hanger attachment bore 22a of the insert.Preferably, the several parts 36a, 38a, and 40a of the load bearingmember 18 are adhesively bonded or otherwise joined to one another. Ifdesired, a cover plate 42a may be secured across the top of the loadbearing member 18a, as shown.

The modified insert 10a is installed and used in precisely the same wayas the earlier described insert 10. Accordingly, it is unnecessary torepeat, in detail, the insert installation procedure. Suflice it to saythat when the insert 10a is properly installed, the acoustic insulatingbarrier' 40a inhibits the transmission of acoustic vibrations from thesupported load to the supporting concrete slab 12.

The modified concrete insert 10b illustrated in FIG. 4 is substantiallyidentical to the insert 10a just described. The major difference betweenthe two inserts resides in the fact that the threaded hanger attachmentbore 22b of the insert 10b extends all the way through the load bearingmember 18b of the insert to provide more secure attachment to thethreaded hanger rod, or the like, to be attached to the insert. Themodified insert 10b is installed and used in precisely the same way asthe earlier inserts of the invention. Accordingly, it is unnecessary torepeat the installation procedures. Suffice it to say that the modifiedinsert 10b is acoustically insulated by the insert 10a, just described.Accordingly, it will be understood that the insert 10b inhibits thetransmission of acoustic vibrations from the supported load to thesupporting slab 12.

As noted earlier, the pan joists 14 illustrated in FIG. 1 are reusableand, therefore, are removed from the completed concrete slab 12. Inother cases, permanently installed pan joists may be employed. FIG. 6illustrates a modified pan joist 140 of this type. In this case, anumber of the pan joists 140 are installed on a scaffold (not shown) andjoined side by side in much the same way as the pan joist 14. Theconcrete slurry is then poured over the joists and allowed to set toform a completed concrete slab 12. The joists 140' are left in place tobe permanent parts of the completed slab.

FIGS. 6 and 7 illustrate a modified, acoustically insulated insert foruse with such permanent pan joist installations. This modified insert isidentical to the insert 10a, illustrated in FIG. 3, except for theomission on the lower supporting base and shield of the insert and theelongation of the insert supporting flanges 24c, whereby these flangesmay extend over two adjacent tubular sections of the pan joists 140, asshown. When making the concrete ceiling-floor slab 12, the pan joists140 are first installed on top of a suitable supporting scaffold (notshown) and are joined side by side to form the lower boundary wall of aconcrete form for this slab. The inserts 10c are then placed in positionon the pan joists, in the manner illustrated in FIG. 6. Thus, whenproperly installed, the supporting flanges 240 of each insert overlie,in supporting engagement, two adjacent tubular sections of the joistsand the lower end of the main body of the insert protrudes through anopening in the intervening web joining the tubular joist sections. Aconcrete slurry is now poured over the pan joists in such a way that theslurry flows into the channels between the adjacent tubular joistsections and around the inserts 100 within these channels. The insertsare thereby anchored in the finished slab 12. It is evident, of course,that inserts "designed for this latter method of installation do notrequire the lower supporting base and shield embodied in the earlierforms of the invention. Thus, in this latter method of installation, thepan joists 14c, which remain as an integral part of the finished slab12, serve as shields to prevent the entrance of concrete slurry into thethreaded hanger attachment bore of the inserts.

Reference is now made to FIGS. 8 through 11 which illustrate anacoustically insulated hanger 100 according to the invention which isadapted to besecured or attached to an insert 102 embedded within anexisting concrete ceiling-floor slab 104. Insert 102 is conventional andthus need not be explained in detail. Suflice it to say that the insertembodies a sheet metal housing 106 which is embedded within the slab104. This housing contains a cavity having an open lower end bounded byupwardly presented shoulders 108. Supported on these shoulders is a nut110.

The present hanger 100 comprises a main body 112 which is similar tothose of the present concrete inserts. Thus, the hanger body 112includes an outer conical shell 114, an inner conical core 116, and anintervening barrier or sleeve 118 of acoustic insulating material.Extending axially through and opening through the lower end of the innercore 116 is a threaded bore As in the acoustically insulated inserts ofthe invention, the outer shell 114 and inner core 116 are composed of arelatively strong material, such as metal. The intervening acousticinsulating barrier or sleeve 118 is composed of a suitable acousticinsulating material, such as rubber. Extending diametrically across andwelded to the upper edge of the outer hanger body shell 114 is a rigidyoke 122. Rigidly joined to and extending from the center of this yoke,along the axis of the hanger body 112, is a threaded stud 124.

In use, the upper stud 124 of the hanger 100 is threaded in thepreinstalled insert nut 110. The hanger than depends below the concreteslab 104, as shown. A threaded hanger bolt 126 attached to the load tobe supported is then threaded in the lower bore 120 of the hanger. Itwill now be understood, therefore, that the load is supported on theslab 104 through the intervening hanger 100 of this invention. Thishanger, being acoustically insulated in the same way as the earlierconcrete inserts of the invention, inhibits the transmission of acousticvibrations from the load to the concrete slab.

It is now evident, therefore, that the invention herein described andillustrated is fully capable of attaining the several objects andadvantages preliminarily set forth.

Although specific embodiments of the present invention have beenillustrated and described herein, it will be understood that the sameare merely exemplary of presently preferred embodiments capable ofattaining the objects and advantages hereinbefore mentioned, and thatthe invention is not limited thereto; variations will be readilyapparent to those versed in the art, and the invention is entitled tothe broadest interpretation within the terms of the appended claims.

What is claimed is:

1. An insert for attaching a load to the underside of an overheadconcrete slab which is cast by pouring a concrete slurry into aconfining form having a lower boundary wall, said insert comprising:

an insert body including a main load bearing member having a normallylower end and a supporting base secured to said member,

said load bearing member having a longitudinal axis and includingattachment means on said axis at the lower end of said member forsecuring said load to said load bearing member in suspended positionbelow said member, and

said supporting base having normally lower downwardly presented surfacemeans at the lower end of said member disposed in a plane transverse tosaid axis and adapted to be placed in supporting contact with the upperside of said boundary wall to support said insert on said wall whilesaid concrete slurry is poured into said form and about said insert toanchor the insert in the finished slab, and supporting base including aplastically deformable portion for adjusting the angle between saidsurface means and axis and retaining said surface means in adjustedangular relation to said axis.

2. An insert for attaching a load to the underside of an overheadconcrete slab which is cast by pouring a concrete slurry into aconfining form having a lower boundary wall, said insert comprising:

an insert body including a main load bearing member having a normallylower end and a supporting base secured to said member,

said load bearing member having a longitudinal axis and includingattachment means on said axis at the lower end of said member forsecuring said load to said load bearing member in suspended positionbelow said member,

said supporting base having normally lower downwardly presented surfacemeans at the lower end of said member disposed in a plane transverse tosaid axis and adapted to be placed in supporting contact with the upperside of said boundary wall to support said insert on said wall whilesaid concrete slurry is poured into said form about said insert toanchor the insert in the finished slab, and said supporting baseincluding adjustable means for adjusting the angle between said surfacemeans and axis and retaining said surface means in adjusted angularrelation to said axis,

said supporting base comprising a plastically deformable sleevecoaxially secured at one end to the lower end of said load bearingmember about said attachment means and extending below said member, anda lower wall member closing the lower end of said sleeve and adapted toseat against said boundary wall, whereby said lower wall member isexposed at the underside of said finished slab when said boundary wallis removed, and said lower wall member having an opening to provideaccess to said attachment means when said boundary Wall is removed, andsaid wall member providing said surface means and said sleeve beingbendable to adjust the angle between said wall member and said axis,whereby said sleeve constitutes said adjustable means.

3. An insert according to claim 2 including:

removable closure means sealing said opening.

4. An insert to be embedded in a concrete slab for attaching a load tosaid slab, comprising:

an outer rigid conical sleeve member, an inner rigid core memberconcentrically positioned within and having approximately the same coneangle as said outer member, and an intervening conical acousticinsulating sleeve of substantially uniform wall thickness positionedbetween said members for inhibiting transfer of acoustic vibrationsbetween said mem bers,

first attachment means at the large end of said outer sleeve member,

second attachment means at the small end of said core member andaccesible through an opening in the small end of said outer sleevemember,

said attachment means being adapted for connection to said load andconcrete slab, respectively, in a manner such that said core member issubjected to a longitudinal force directed toward said opening, and thediameter of said opening being substantially smaller than the diameterof the large end of said core member, whereby said members arepositively restrained against axial separation under load and saidinsulating sleeve is subjected substantially only to a compressionloading,

said first attachment means comprising laterally projecting lugs on saidouter sleeve member for effecting firm anchorage of said outer sleevemember in said slab, and

said second attachment means comprising a threaded bore extendingaxially into the small end of said inner core member.

5. A hanger to be attached to an insert embedded within a concrete slabfor anchoring a load to said slab, comprising:

an outer rigid conical sleeve member, an inner rigid core memberconcentrically positioned within and having approximately the same coneangle as said outer member, and an intervening conical acousticinsulating sleeve of substantially uniform wall thickness positionedbetween said members for inhibiting transfer of acoustic vibrationsbetween said members, first attachment means at the large end of saidouter sleeve member,

second attachment means at the small end of said core member andaccessible through an opening in the small end of said outer sleevemember,

said attachment means being adapted for connection to said load andconcrete slab, respectively, in a manner such that said core member issubjected to a longitudinal force directed toward said opening, and thediameter of said opening being substantially smaller than the diameterof the large end of said core member, whereby said members arepositively restrained against axial separation under load and saidinsulating sleeve is subjected substantially only to a compressionloading.

said first attachment means comprising a threaded stud on the commonaxis of said members and secured to the large end of said outer sleevemember for threaded engagement with said insert, and

said second attachment means comprising a threaded bore extendingaxially into the small end of said 9 10 inner member for receiving athreaded hanger bolt FOREIGN PATENTS attached to said 888,202 1/1962Great Britain.

BOBBY R. GAY, Primary Examiner UNITED STATES PATENTS 5 A. M. CALVERT,Assistant Examiner 1,145,385 7/1915 Marble 52-707 3,290,851 12/1966Sherburne 52701 US. Cl. X.R. 1,088,290 2/1914 McAllister 52-707 52 707References Cited

